Various types of plastic bag containers utilize a pair of closure strips respectively having male and female members which interlock together to close the open end of the container and seal the interior from the external environment. The strips and associated container are typically formed from thermoplastic material. The strips are usually formed by extrusion and then connected to the side walls of the container circumscribing the open end by heat sealing or other suitable fastening means. The closure strips and container body may also possibly be formed as a single piece by extrusion.
The interlocking closure strips on the bag bodies are particularly useful for improving the longevity of contents in the container when the closure is fully closed by sealing such contents from the external ambient environment. The closure fastening strips and the bag bodies themselves are generally transparent and the strips therefor have the same general appearance as the bag body. In other words, it is often difficult to actually determine whether the male and female closure strips are fully mated together, so as to completely seal the bag interior.
The above misalignment problem occurs from the user's inability to visually identify when the interlocking closure strips are fully mated to form a seal. As a means for enabling such visual verification, it is known to use a color change means wherein male and female interlocking members having different colors are employed and, upon successful interlocking, blend to provide yet a different color. For example, in U.S. Pat. No. 4,829,641 to Williams, assigned to First Brands Corporation, Danbury, Conn., there is disclosed an interlocking closure device wherein two closure elements are oriented to be interlocked over a predetermined length to seal a bag. Each of the closure elements has different colors for establishing visually the completeness of the mating of the closure elements by providing a color different from the closure elements when the closure elements are successfully and fully fastened. Therein, a color change enhancement member is introduced in an internal channel of a translucent closure element so that the closing and opening of the closure device is more easily detected by visual inspection.
Numerous problems exist in the aforementioned patent and other prior art devices wherein different colors are employed and upon successful interlocking provide yet a different color. For example, in the aforementioned patented prior art, the male and female interlocking members are completely colored instead of being formed from transparent material such as clear resin. The requirement that a colored resin be employed for the entirety of these male and female closure members instead of a clear resin unnecessarily increases costs, i.e., clear resin is less expensive than colored resin.
Another problem associated with the aforementioned prior art is that care must be exercised to insure that two different colors are being used which can be successfully blended together while providing the ability to visually confirm full closure. For example, separate colors to be blended into a third color must be selected so that sufficient contrast is provided between the blended color and the separate colors.
It is accordingly one object of the present invention to enable a user to easily verify whether two closure elements are completely interlocked together.
Another object is to facilitate visual inspection and confirmation of complete interlocking without utilizing additional ribs or guide members on colored interlocking closure devices or by utilizing color change members.
Still another object is to enable visual inspection of a completely interlocked closure device to occur by utilizing the presence of colors but without requiring color change by color blending.
Another object is to utilize color to visually confirm complete interlocking with a minimum of or without color resin to thereby reduce manufacturing costs.